The present invention relates to lasers and, more particularly, to white-light lasers.
Lasers are a well-known technology with many applications in a wide variety of areas such as projection display and telecommunications. Typical lasers generate a monochromatic, single-wavelength beam of coherent, collimated light. It is also useful to produce polarized laser light and such beams of light are widely used in optical applications. There are also applications for beams of white laser light including several individual wavelengths of light that, taken together form a white color.
Means to create white-light lasers are known in the art. For example, U.S. Pat. No. 5,418,803 titled, xe2x80x9cWhite Light Laser Technologyxe2x80x9d issued May 23, 1995 to Zhiglinsky et al. and U.S. Pat. No. 5,428,635 titled, xe2x80x9cMulti-Wavelength Tunable Laserxe2x80x9d issued Jun. 27, 1995 to Zhiglinsky et al. describe a laser capable of generating polychromatic or white-light radiation by employing a diffraction grating and reflecting element as the ends of a simple laser resonator cavity. The dispersive element either solely or in combination with an intra-cavity lens is arranged such that each wavelength component of the white-light radiation is amplified by a different portion of the active medium. Forced oscillation or positive feedback for each wavelength component is achieved by operating the diffraction grating in an auto-collimation configuration. This technique requires the use of special diffraction grating or intra-cavity lens elements, is complex to manufacture, and includes multiple layers of active medium within the resonant cavity. Moreover, it does not provide a thin, low-volume laser device and the efficiency of the device suffers from supporting multiple wavelength emission from a single cavity. Nor does this technique support the production of polarized white light.
White laser light can also be formed by combining individual laser beams as described in U.S. Pat. No. 5,614,961 titled, xe2x80x9cMethods And Apparatus For Image Projection, issued Mar. 25, 1997 to Gibeau et al. by utilizing three linear laser arrays. Each linear array generates multiple (N greater than 1) parallel output beamlets at one of the three primary colors (red, green, blue). The corresponding beamlets are combined spatially to form a single white-light linear array source. Through a projection/scanner optical system, the beamlets of the white-light source are simultaneously directed to, and swept horizontally across a distant viewing screen. Such a design requires complex beam combining optics, separate laser light generators, and does not create polarized light.
In yet another alternative, a white-light beam is created by sequentially outputting colored light, as in a filter wheel, by rotating a laser light source. For example, U.S. Pat. No. 5,764,663 titled, xe2x80x9cLaser Apparatusxe2x80x9d issued Jun. 9, 1998 to Ouchi et al. describes a laser apparatus for generating laser beams of predetermined wavelengths comprising a solid-state laser medium for generating a light beam having predetermined at least three fundamental wavelengths; at least three wavelength converters which respectively convert the light beam into harmonics corresponding to three primary colors of blue, green, and red, the wavelength-converters being circumferentially arranged; wavelength-converter holder for holding the wavelength converters; light blocking portions disposed between the wave length converters; rotating unit for rotating the wavelength-converter holder, thereby repeatedly positioning each of the wavelength converters and each of the light blocking portions on an optical axis of the solid-state laser medium; and a laser resonant optical system which resonates the light beams generated by the solid-state laser medium and outputs the harmonics converted by the wavelength converters. This method requires a mechanical rotation that is cumbersome and prone to failure and it is not capable of generating polarized light.
U.S. Pat. No. 4,021,845 titled, xe2x80x9cLaser For Generating White Lightxe2x80x9d issued May 3, 1977 to Wang describes a laser structure for generating white laser light when energized by a source of dc voltage. The laser tube structure comprises a gas-filled envelope having a longitudinal axis and an anode electrode forming a portion of the envelope. A hollow cathode is positioned within the envelope and coaxially disposed with respect to the anode electrode portion of the envelope. Members are coaxially aligned with the ends of the envelope such that a structure is provided for confining a gaseous medium therein; a dc voltage applied between the cathode and anode electrode creating a discharge there-between, the discharge stimulating continuous wave laser emission along the longitudinal axis of the cathode, the laser emission comprising simultaneous multi-line emissions in the form of white light. This technique requires the use of a gas-filled tube and is also complex to manufacture, does not provide a thin, low-volume laser device, and does not produce polarized light.
There is a need, therefore for an alternative white-light laser that avoids these limitations.
The need is met according to the present invention by providing a white-light laser integrated structure that includes a substrate and one or more individually addressable laser light pixels formed on the substrate for emitting a white beam of laser light perpendicular to the substrate. Each of the one or more individually addressable laser light pixels include one or more organic light emitting diodes (OLEDs) and a plurality of organic vertical cavity lasers that are arranged to be optically pumped by the one or more OLEDs. The plurality of organic vertical cavity lasers emit differently colored light and the one or more individually addressable laser light pixels emits substantially white light when the differently colored light is combined.
Another aspect of the present invention provides a polarized white-light laser, that includes a substrate and one or more individually addressable laser light pixels formed on the substrate for emitting a white beam of laser light perpendicular to the substrate. Each of the one or more individually addressable laser light pixels includes one or more organic light emitting diodes (OLEDs) and a plurality of organic vertical cavity lasers, having an asymmetric shape and producing polarized light. The one or more individually addressable laser light pixels are arranged to be optically pumped by the one or more OLEDs. The plurality of organic vertical cavity lasers emit differently colored light and the one or more individually addressable laser light pixels emits substantially white light when the differently colored light is combined.
A third aspect of the present invention provides a system for producing an array of image elements forming a collimated beam of patterned white-light, that include: a controller and connections; a plurality of individually addressable laser light pixels formed on a common substrate responsive to the controller for producing the array of image elements; and each of the plurality of individually addressable laser light pixels include one or more organic light emitting diodes (OLEDs) and a plurality of organic vertical cavity lasers that are arranged to be optically pumped by the one or more OLEDs, wherein the plurality of organic vertical cavity lasers emit differently colored light perpendicular to the substrate and the plurality of individually addressable laser light pixels emits substantially white light when the differently colored light is combined.
The fourth aspect of the present invention provides a method for creating a white-light laser including the steps of: providing a substrate; and forming one or more individually addressable laser light pixels on the substrate, wherein each of the one or more individually addressable laser light pixels include one or more organic light emitting diodes (OLEDs) and a plurality of spatially distributed organic vertical cavity lasers for emitting a white beam of laser light perpendicular to the substrate from a plurality of different colored light emitted from the plurality of spatially distributed organic vertical cavity lasers.
The present invention has the advantage that a simple integrated structure can be employed to create a white laser with polarized light.